Various compounds act as catalysts in applications to process feedstocks. Suitability of the catalysts depends on factors such as activity, preparation costs, susceptibility to deactivation, and selectivity for desired reactions. The catalysts can thus determine viability of processes such as methanation, which utilizes the catalysts to convert carbon monoxide and hydrogen gasses into methane.
Methanation reactions enable producing substitute natural gas (SNG) from coal by gasifying the coal to generate synthesis gas (syngas) and converting the syngas to the SNG via the methanation. Declining supplies of natural gas being produced and expanding demand for the natural gas cause natural gas prices to rise. Since coal resources are often more readily available than natural gas resources, the methanation provides an option for distributing these available energy sources as needed.
Prior compounds and preparation techniques for the compounds used as the catalysts in the methanation reactions impose operating limitations or prevent economic feasibility. Sulfur poisons nickel based compounds used for the catalyst in the methanation such that sulfur impurities from the feedstock must be removed within tolerances of the nickel based compounds. In addition, utilizing the nickel based compounds requires adjusting a hydrogen/carbon monoxide ratio since carbon deactivates the nickel based compounds. While prior molybdenum disulfide products when used as the catalyst for the methanation may lack such restrictions with respect to carbon and sulfur feedstock content, previous methods produce the molybdenum disulfide products with limited performance and/or require expensive precursor compounds such as ammonium tetrathiomolybdate.
Therefore, a need exists for metal sulfide catalysts and methods of preparing such catalysts.